1. Field of the Invention
The present invention relates to a detection device which includes an elastically deformable contact element and in which detection output varies with the amount by which the contact element is pressed.
2. Description of the Related Art
Input units of game controllers, etc., contain detection devices for obtaining detection outputs which correspond to input operations using operation buttons. Some detection devices detect only an ON-OFF operation, and in other detection devices, the detection outputs vary with the amounts by which the operation buttons are pressed.
Such detection devices, in which the detection outputs vary with the amounts by which the operation buttons are pressed, are constructed as follows. That is, a resistive element formed of a resistive material having a relatively high resistivity is disposed on a substrate, and an elastically deformable element formed of a resistive material having a lower resistivity than the resistive element is used as a contact element for contacting the resistive element.
When the contact element having a relatively low resistivity is pressed against the resistive element having a relatively high resistivity and the contact area therebetween is changed, the total resistance of the resistive element and the contact element is also changed. Accordingly, the detection output is also changed.
In the case in which a game apparatus, etc., contains such a detection device as described above and is controlled based on the detection output, the total resistance preferably varies linearly with the contact area when the contact element is pressed. In addition, it is necessary to make a variation range of the detection output, in which the detection output varies with the contact area between the resistive element and the contact element, as wide as possible. However, the linearity of the resistance variation and the variation range of the detection output contradict each other; when the linearity is improved, the variation range is reduced, and when the variation range is increased, the linearity is degraded.
In addition, in the case in which current is applied to the resistive element and the variation of the contact area between the resistive element and the contact element is determined based on a voltage variation, the detection output is affected by resistance variation caused due to temperature variation of the environment. In addition, when multiple detection devices are manufactured, the detection output is also affected by the differences in resistances of the resistive elements which occur in the manufacturing process.
Accordingly, in order to solve the above-described problems, it is an object of the present invention to provide a detection device in which the linearity is improved and a wide variation range is obtained, and in which the detection output is not affected by the temperature variation, etc., in the environment.
According to the present invention, a detection device includes a first resistive element; a second resistive element which is serially connected to the first resistive element; and a contact element which is elastically deformable and has a smaller resistivity than the first resistive element. When the contact element is pressed against a first resistive element, a contact area between the contact element and the first resistive element varies in accordance with a pressing force. A predetermined voltage is applied to the first resistive element and the second resistive element, and a detection value is given from the potential between the first resistive element and the second resistive element. In addition, a resistance ratio of the first resistive element to the second resistive element (resistance of the first resistive element/resistance of the second resistive element) is 3 or less.
Preferably, the resistance ratio (resistance of the first resistive element/resistance of the second resistive element) is 1 or more.
According to the present invention, the second resistive element has a fixed resistance, and the detection output is determined by obtaining a resistance variation, which is caused when the contact element contacts the first resistive element, based on the variation of the ratio of the variable resistance to the fixed resistance.
It is not necessary that the second resistive element be formed of a single resistor; it may be formed of a plurality of resistors which are connected in either a parallel or serial manner. In addition, the first resistive element may also include a plurality of resistors which are connected in either parallel or serial manner, and the resistors may be individually provided with contact elements for contacting the resistors.
The contact element may be provided to an operation button which projects outward from a casing and which can be pressed inward, and a detection output may be obtained in accordance with the contact area between the contact element and the first resistive element which varies when the operation button is pressed.
According to the present invention, the detection device in which the detection output varies with the amount by which the contact element is pressed is obtained. In addition, the detection output has an improved linearity and high resolution, and the operability is not degraded.